1. Technical Field of the Invention
The present invention relates to a noise reduction device for reducing noise produced on rotation of a motor mounted in a starter.
2. Related Art
Recently, in order to reduce carbon dioxide emitted by a vehicle and to improve fuel efficiency, these is an increase in a vehicle with a function to cut fuel supply to an engine to automatically stop an engine on stopping at a signal light at an intersection. This function is also called an “idling stop function”. By this function, the engine is stopped. After that, a start operation is carried out by a user. In response to the start operation, a starter is activated by instruction of an ECU (electronic control unit) to automatically restart the engine.
On the other hand, in a starter using a commutator motor, a spark may be generated between a commutator and a brush during rotation of the motor. The spark causes noise to be generated in devices such as radios, which gives a user a sense of discomfort.
With respect to such a problem, DE-A-102008001570 discloses a technique for suppressing noise generated from the motor by using a capacitor circuit with at least one capacitor connected in parallel with the motor.
In the capacitor circuit disclosed in DE-A-102008001570, the capacitor is connected to an electrode by soldering. In a starter used under environment of severe temperature conditions, cracks can be produced by thermal fatigue during soldering to cause malfunction of a noise reduction device itself.
In order to increase performance of the noise reduction device, a capacitor with large capacitance may be needed. In this case, a plurality of capacitors are required to be built in a circuit. This induces an increase in man-hour. It is thus desired to efficiently assemble the plurality of capacitors at low cost.